Calibration

Before we did any more complex adjustments, we changed some of the basic picture settings on the Toshiba 32SL753, to get an idea of how the TV might perform for the average user who doesn’t have access to measuring equipment and software. Because the Toshiba 32SL753B has two controls which affect Gamma in unpredictable ways, we left these at their defaults, and shut both of the Noise Reduction filters off.

Greyscale

Pre-calibration CCT in [Movie] mode

Pre-calibration RGB tracking and delta errors (dEs)

The image put out by the Toshiba 32SL753 in its relatively untouched “Movie” mode had a visible orangey/yellow cast to it, giving otherwise neutral material a slightly “baked” look. In addition to this, the Toshiba 32SL753B comes set up to reproduce a Gamma of around 2.5, which means that the entire picture may appear quite dark unless the HDTV is viewed in a dark room (it would make sense if this was Toshiba’s intended use for the “Movie” mode). Gamma is one of the few variables in display calibration where some “wiggle room” exists; although Greyscale and Colour are precisely specified, there exists a lot of debate over Gamma, with the general consensus being that 2.2 should be adopted for standard daytime viewing and 2.5 for completely light-controlled specialised viewing rooms. For consistency with our other reviews and to reflect general purpose viewing, we chose to calibrate to 2.2.

Uncalibrated [Movie] mode curve

Corresponding gamma tracking

The Toshiba 32SL753 features a basic [Colour Temperature] control, which can be set from 0-10. Through measuring, we found that the best starting point was 5. After this has been set, the calibrator (or DIY user) can use a standard two-point Greyscale calibration system to adjust colour temperature further. We also adjusted the [Static Gamma] control and found that a setting of -2 was best for reaching our desired 2.2 gamma. The [Black/White Level] control was best set to 0.

Post-calibration CCT in [Movie] mode

Post-calibration RGB tracking and dEs in [Movie] mode

After calibration, the Toshiba 32SL753B produced a suitably familiar colour of white, bringing a good amount of natural colour back to the picture. As is often the case with LCD TVs, a blue tinge persisted in the deepest black areas (see 10% stimulus on the above RGB Level Tracking chart). We attempted to calibrate with the intention of specifically removing this, but this degraded Greyscale quality elsewhere across the range.

You may notice that the mix of Red, Green and Blue breaks apart at 90 and 100%. Normally we can fix these small inaccuracies by lowering the TV’s Contrast control, but in this case, it made no difference. However, in practice, it did not produce a visible discolouration.

Additionally, after battling our way through the many different possibilities of Gamma settings, we were very satisfied with the Toshiba 32SL753′s performance in this area.

Gamma curve in [Movie] mode

Corresponding gamma tracking

Colour

Toshiba has been shipping its LCD TVs with a semi-broken 3D Colour Management system for some time now, and sadly, the 32SL753B does not buck that trend. While control over Hue, Saturation and Brightness are promised, we’ve always found that adjusting the latter control brings out terrible artefacts in the video, resulting in previously calm-looking parts of the picture appearing overrun by noise. After verifying that this was still the case, we set about using the remaining two controls (Hue and Saturation) to clean up colour reproduction.

As it happens, the “Saturation” control in the Colour Management menu actually affects both Saturation AND Brightness, but does not introduce the aforementioned noise. Ideally, we would have liked to fully saturate red, but in order to do this, its Luminance would be much too high, resulting in the colour looking very bright on-screen. The visibly undersaturated red indicated by the CIE chart (top) is, sadly, the best we could manage, and indeed, is no better than the Toshiba 32SL753B’s out-of-the-box condition. Fortunately, we could clean up the other colours to a much more satisfactory standard. It’s interesting to note that Samsung’s LED side-lit TVs have also had difficulty in fully saturating Red, although not to the same extent shown here.

The end result is not ideal, but the red saturation deficiency is actually much less noticeable on-screen than you may think from looking at the above chart. Had the Toshiba 32SL753 suffered from a red Luminance deficiency instead, the situation would not be so positive (Sharp’s most recent Quattron LED LCD TV featured deficiencies in Green and Yellow, which was very “sickly”-looking colours at times). Thankfully, colour Luminance (or colour brightness) levels were suitably close to perfection, meaning that most of the richness of the colours was still conveyed.

Other colours could be brought into roughly accurate positions, but this was essentially the result of trial and error. Rather than aligning Hue and Saturation+Luminance individually, our calibration basically consisted of altering the controls and “seeing what stuck”, before settling on the values that gave the lowest error reading.

Another interesting point here is that surprisingly, the Toshiba 32SL753B actually arrives with its [Colour] control set too low, rather than too high. We had to raise this setting to around 8 from its default position of 0 to bring colour luminance levels to roughly correct positions, before starting further tweaks with the Colour Mangement menu. In particular, when we first received the Toshiba 32SL753, the colour of Green was too dark, yet over-saturated. We imagine Toshiba has done this to make the colour seem superficially “deeper”, but this is irrelevant since HDTV (and standard-def TV, for that matter) precisely specify what the colours should look like.